#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <unordered_map>
// 正则表达式匹配：https://leetcode.cn/problems/regular-expression-matching/description/
using namespace std;
class Solution {
public:
    bool isMatch(string s, string p) {
        int m=s.size();
        int n=p.size();
        s=" "+s;
        p=" "+p;
        vector<vector<bool>> dp(m+1,vector<bool>(n+1));
        dp[0][0]=true;
        for(int i=2;i<=n;i+=2)
        {
            if(p[i]=='*')
                dp[0][i]=true;
            else 
                break;
        }
        for(int i=1;i<=m;i++)
        {
            for(int j=1;j<=n;j++)
            {
                if(p[j]=='.')
                    dp[i][j]=dp[i-1][j-1];
                else if(p[j]=='*')
                {
                    if(p[j-1]=='.')
                        dp[i][j]=dp[i-1][j]||dp[i][j-2];
                    else
                        dp[i][j]=(s[i]==p[j-1]?dp[i-1][j]:dp[i][j])||dp[i][j-2];
                }
                else
                    dp[i][j]=(s[i]==p[j])?dp[i-1][j-1]:dp[i][j];
            }
        }
        return dp[m][n];
    }
};